WiMAX (Worldwide Interoperability for Microwave Access) is a recently introduced broadband wireless access technology, standardized in IEEE 802.16e. One problem occurring in existing WiMAX systems is the level of interference being experienced, particularly in relation to uplink (UL) interference from mobile stations of adjacent cells. Specifically, WiMAX UL system performance is limited by adjacent interference power from these mobile stations.
In order to guarantee the system performance for users on a cell edge, it is important to limit the UL Interference over Thermal (IoT) criterion from adjacent cells, as is known in the art. For example, in Long Term Evolution (LTE) broadband wireless communication systems, it is known to pass an L2 message describing measured adjacent cell IoT between cells. This message can then be used in UL power control, such as fractional power control. The result of the UL power control is tightly controlled IoT level at a base station. However, in WiMAX systems this type of L2 messaging does not exist. As a result, each base station has no knowledge of interference being experienced on neighboring cells. Although the current WiMAX system includes a scheduler and resource allocation that can efficiently schedule users and allocate resources, the UL interference IoT is not tightly controlled.
In addition, there have been some reports that up to 85% of WiMAX mobile stations transmit at full power. Not only does this contribute to interference problems, this directly equates to reduced battery life in mobile stations, which is also of interest to WiMAX customers.
What is needed is a technique to control IoT by reducing the power that a mobile station requires to achieve reliable WiMAX communications, which also serves to extend battery life in the mobile station. It would also be of benefit to provide this IoT control without the knowledge of adjacent cell IoT information.
Skilled artisans will appreciate that common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted or described in order to facilitate a less obstructed view of these various embodiments of the present invention.